The present invention relates to an optical device with a high collection efficiency and to a cytofluorimeter using said device. It is more particularly used in the analysis of a flow or flux of biological cells.
Cytofluorimeters are known in which the light emitted by a flow of biological cells, illuminated by a laser, is collected by a microscope objective located at a considerable distance from the flow of cells being investigated and which has a small aperture, so that it only collects a small amount of light coming from the cells.